Keyboard



May 10, 1955 J. A. MATHEWS ETAL KEYBOARD 2 Sheets-Sheet 1 Filed Oct. 15, 1952 IN V EN TOR.

YJOSEPH A IVEUYIEWS B and HAROLD WHEELER ATTORNEY y 10, 1955 J. A. MATHEWS ETAL 2,707,896

KEYBOARD 2 Sheets-Sheet 2 Filed Oct. 15, 1952 5 W m u V NM 1 M m, E S m Y B w 1 HA R OLD WHEELER ATTORNEY United States Patent Berwyn, IlL, assignors tries, Inc.,

and Harold- Wheeler, to Central Commercial Indus- Cook County, Ill'., a corporation Application October 15, 1952, Serial No. 314,828 4 Claims. (Cl. 84-423) This invention relates to keyboard musical instruments and particularly to instruments of the class employing electrical'tone producers which are selectively activated for musical expression from the instruments keyboard.

Certain of the more important features of the invention, are:

(l) The provision of an organization of elements for springing. the keys of the instruments keyboard and for operatively relating to each separate playing-key thereof an electric switch which is operated by the key from an on condition when playing pressure is applied tothe key to an off condition when said pressure is removed from the key.

(2) The provision of an organization of elements embodying certain new and novel features enabling. con veniently springing the keys of the keyboard of a musical instrument and concurrently correlating electric switches with said keys by an exceedingly simple method.

(3) The provision of a keyboard whose case has a common mounting for key-operated electric switches and means for springing the keys of said keyboard, to which mounting, the said switches and said springing means can be attached from outside said case and the mounting then positioned to dispose the springing means and the switches inside said case in coactive relation. tov said keys.

(4) The provision of means in an electrical musical instrument whereby all playing-key-operated electric switches can be disposed outside the instruments case for quick and convenient access thereto for cleaning, repairing and replacement of parts as and when occasion therefor arises.

The above and further objects of the invention will be more readily understood from the following description of an exemplification thereof, reference being had to the accompanying drawings wherein:

Figure 1 is a perspective view of the device set up, the music rack being shown in an applied position in full lines and in a partly removed condition by dot and dash lines;

Figure 2 is a view in perspective of the device in a partly folded condition;

Figure 3 is a perspective view on a somewhat enlarged scale of the superstructure of the device showing the cover of the case opened for a clear understanding of the key springing means and the key-operated electric switches;

Figure 4 is a transverse sectional view of the case portion of the device with the cover partly closed so as to illustrate the method of correlating the springs and the electric switches with respective playing-keys of the keyboard;

Figure 5 is a view similar to Figure 4 showing the cover fully closed and retained against swinging movement, and

Figure 6 is a perspective view of one of the, electric switches.

I-n carrying the invention into practice use is made of a superstructure 10 in the form of a rectangular case,

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and an understructure consisting of foldable end legs 11 and 12, which, when the case is set up as shown at Figure 1 enables. the case to be supported at. an elevation to support the keyboard 12a in a playing position. When thus set up, collapsible braces. 13 which connect the legs with the bottom of the superstructure serve to hold the device in a relatively firm and rigid condition.

The keyboard 12a comprises a mounting 14 which fits inside the case-like superstructure as shown at Figures. 4 and 5, which mounting includes a fulcrum bar 15 and a backstop bar 16. The keys 17 are of the conventional construction typical of organs and pianos. The superstructure is bounded by a longitudinal back board 18, ends 19, a front rail 20, a bottom board 21, and a cover 21a, the latter hinged to said back board 18 as at 22 in a manner enabling it to be tilted to an opened position as shown at Figure 4 and to be tilted downwardly and forwardly to the closed position shown at Figure 5. The cover is of less width than the case-like superstructure so that when closed as shown at said Figure 5, it closes over only the back ends of the playing-keys 17. By this arrangement, the effective playing surfacesof the keyboard are exposed so that the keyboard can be played from the front of the case when the device is set up.

It is noted that when the cover is raised to its opened position. of adjustment as shown at Figure 4, the playingkeys tilt downwardly and forwardly, the under surfaces at the front ends of the keys resting on felt strips 23, the back ends of the keys being raised slightly above the felt faced stop bar 16. When the cover is closed as shown at Figure 5,. the under surfaces of the front ends of the keys are slightly raised from the felt strips 23 and the back ends of the keys are in free resting engagement with said felt faced stop bar 16 by virtue of yielding pressure placed upon the back ends of the keys by the springing means to be referred to presently.

As the device deals mainly with a type of electrical musical instrument wherein electrical tone generators are activated by electric key-operated switches which must be accurately related to the playing-keys in order that the time interval for activating. any of the switches will be the same, we prefer to use the type of switch disclosed in the application of Merwin J. Larsen, Serial No. 289,141, filed May 24, 1952. No claim is made for these switches except in the disclosed environment and combination thereof with other elements of the herein disclosed improvements.

Attached to the under side of the cover 21a is a rigid bar 24, the back edge of which is tapered downwardly and forwardly as at 25. Attached at 26 to the tapered portion of said bar are downwardly and forwardly extending fiat leaf springs 27. As shown at Figure 3, said springs are equi-distantly related to each other longitudinally of the device and arranged with respect to the playing-keys so that the curved lower ends 27a of the springs come against the back ends of the keys when the cover 21 is closed as shown at Figure 5. It follows that by this arrangement, all keys of the keyboard are simultaneously sprung when the cover is fully lowered and is held fixed to the body portion of the superstructure, such, for example, by lag screws 28 which are insertable in openings 28a in the cover and engageable in corner blocks 28b inside the structure 10.

Forwardly of the bar 24 and in parallel relation thereto is a rigid bar 29 on the under side of which electric switches 24a are mounted, the number of the switches being the same as the number of key loading or tensioning springs 27, so that for each key there will be a spring 27 and an electric switch 24a, which will be individual thereto and will be operated by the key from an elf condition when the key is in a playing position as shown in Figure 5 to an on condition when the key is depressed as shown at Figure 4.

Following the form and general construction of the playing-key-operated switches disclosed in the aforementioned application of Merwin I. Larsen, the herein illustrated switch assembly comprises a flap strip 31 of Bakelite or other well-known relatively inflexible electrical insulating material to which longitudinally spaced-apart members 32 are riveted as at 31a at the front ends of said members. Coil circuit making and breaking springs 33 have their forward ends attached to said rivets and their opposite ends to lugs 32a on said members so that under the normal urge of the springs the members 10 are to be tilted to the position shown at said Figure 4.

To this point in the description the structural details of two essential unitary assemblies have been fully described and shown, such that the springs 27 and the individual electric switches 24a are arranged in pairs in order that and as aforementioned there will be for each individual key 17, one spring 27 and one electric switch 24a. The arrangement of the respective unitary assemblies is such that when the cover 21 is moved from an opened position to a closed position, the forward ends 27a of the springs 27 will come against the back ends of the playing-keys so as to urge said ends downwardly against the felt faced stop bar 16. In this manner, all of the keys are simultaneously loaded or spring so that the keys are in playing positions. Simultaneously with this operation the ends 35 of said members 32 are brought against the upper surfaces of the back ends of the keys. The cover is then secured in a closed position and by depressing the front ends of the keys, the free ends 25 of said members 32 are bent to their permanent angles as shown at Figure 5. In this manner, the keys are sprung to their playing positions and concurrently therewith the members 32 of the electric switches are properly related with the respective keys of the instruments keyboard.

The members 32 each has soldered thereto as at 36 a signal input lead 37. The member 32 is cut out longitudinally at 38 and as shown, the coil spring 33 is so related to the cut out portion of said member as to come against a signal output bus-bar 39 when the member 32 is advanced toward the Bakelite strip 31 in response to playing pressure applied to the key 17.

It is to be understood that when the cover 21 is fully closed against the superstructure 10, the ends 35 of the members 32 will be pressed against by the keys 17 by first manually depressing the front ends of the keys. This tilts the members upwardly and aaginst the Bakelite strip 32 and effects the final bending of said ends 35 to their intended permanent angles. It, therefore, can be assumed that in Figure 5 there has been a first depression of the keys so as to convert said ends 35 from their normal non-permanent angle shown at Figure 4 to the permanent angle shown at said Figure 4.

While we disclaim any of the features of the herein disclosed electric switches 24a, except in the broad combination with other features of the invention, this disclosure will be full and complete with a more detailed description of the nature and properties of the specific metal from which the members 32 are formed. The metal is dead soft steel or equivalent metal, of about 10,000 inch gauge, approximately V of an inch in width and of any suitable length. The metal has a low degree of resiliency and the angular free end 35 of each individual member is relatively ductile. The body portion of each member is of sufiicient strength and rigidity to resist bending under the tension the coactive coil spring 33 which tends to tilt the member to a position where the contact spring is disengaged from said bus-bar 39 when a respective playingkey is in a playing position. By virtue of the described properties of the metal, the end of each separate member 32 is thus readily bendable from an original non-permanent angle to a permanent angle by coaction with the playing-key upon a first depression of the key after lowering the cover 21 and rigidly securing the cover to the superstructure 10 as previously described. It is of course understood that each member 32 functions primarily as a signal conductor for energizing the coactive coil spring 33 and as a playing-key-operated motion imparting means for disengaging the spring from said busbar when the key is in a playing position.

By this new and novel combination of elements a case of pleasing design is provided in which an element of the case, namely the cover 21a, constitutes a common support for the springs 27 and their correlated electric switches. Initially the bars 24 and 29 are attached to the under side of the cover by suitable fastenings, to which part 24, the springs 27 have been previously attached as a common assembly of springs. The strip 31 containing the switches is then attached to the under side of the bar 29, there being some care exercised in the method of attachment thereof so that the switches are correlated to the springs 27. In effect there is a front longitudinal row of electric switches and a back longitudinal row of springs 27, the switches being on a direct line with said springs. At Figure 2 is shown a cable C having a multiple plug P for connection in a tone producing system employing tone signal generators connected in keying circuits and to an electroacoustical translating system. The cable consists of as many lead wires as there are electric switches in the aforementioned assembly of switches and the cable may extend through the bottom board of the superstructure 10 so that the terminal leads may be connected with the respective switches as shown at Figure 3.

We place no particular emphasis on the form of understructure upon which the superstructure 10 is mounted. It is convenient that a device of the class described shall be of light weight and readily portable, yet these features have no functional significance when used with the main features of our invention. It is, therefore, to be understood that the combination consisting essentially of two unitary structures, namely, a set of longitudinally spaced apart electric switches and a set of longitudinally spaced apart key loading springs are of the gist of the invention when combined and related as shown and are mounted upon a common mounting such as the cover 21a or an equivalent structural element which is coactive with a keyboard to associate with each playing key one of the springs 27 and one of the electric switches 24a.

Means are provided for stopping pivotal motion of the playing-keys of the keyboard under the resilient urge of the springs 27. A convenient means to this end preferably consists of a longitudinal rigid bar secured to the under surface of the cover of the structure 10 so as to overlie the keys and engage same when the cover is closed and secured to said structure in the manner aforestated.

What we claim as our invention is:

1. An organization of coactive elements for the purpose described, the same comprising a relatively shallow, upwardly opening case having a keyboard mounted therein; a cover mounted on the case for adjustment from a position of closed adjustment to a position of opened adjustment, said cover being of a dimensional size so that when in its closed position of adjustment, it overhangs only the back ends of the playing-keys of said keyboard and exposes the efiective playing-surfaces of said keys for playing thereof from in front of said case; key springing means on the underside of said cover for imposing a yielding pressure against the back ends of said keys to thereby dispose the front ends of the keys in yieldingly supported playing positions; a stop on the underside of said cover adjacent to the front end thereof to engage the keys when the cover is closed and to stop upward motion of the front ends of the keys under the urging tendency of said springing means; and a system of key-operated electric switches mounted on the underside of said cover and disposed forwardly of said springing means, said system of electric switches embodying a longitudinal row of switches such that one each of the switches is coactive with a respective avozese al key of said keyboard and is adapted to be successively actuated by the key when playing said key.

2. An organization of coactive elements as set forth in claim 1 wherein said cover is hinged to the rear of said case for vertical adjustment from a closed position in which the springing means, and said switches are coactively related to the keys of said keyboard and whereby, when the cover is tilted to an opened position the keys of said keyboard, said key springing means and said electric switches are completely exposed and are accessible from exteriorly of the case.

3. An organization of coactive elements as set forth in claim 1, wherein means are provided for rendering the cover immovable when closed and to maintain a functional relationship of the springing means and said electric switches relative to the respective keys of said keyboard, as and for the purpose described.

5 4. An organization of coactive elements as set forth in claim 1 wherein the forwardly disposed key operated electric switches each includes a resilient switch actuator in yielding engagement with the upper surface of a respective playing-key at a point rearwardly of the effective playing-surface of said key.

Referenees (Iitetl in the file of this patent UNITED STATES PATENTS 449,756 Egan Apr. 7, 1891 727,348 Coggan May 5, 1903 1,837,944 Blum Dec. 22, 1931 FOREIGN PATENTS 558,273 Germany Sept. 5, 1932 

